1. Field of the Invention
The present invention relates to a method of monitoring an electrical power switching module of an underwater installation and a power distribution unit for an underwater installation.
2. Description of Related Art
Underwater facilities, for example subsea well installations such as hydrocarbon production wells, are typically supplied with AC electrical power from the surface via an umbilical cable. At the subsea end, the umbilical terminates in an umbilical termination unit (“UTA”). Switching of this electric power between the various well functions, (including for example a subsea electronic module (“SEM”) of a subsea control module (“SCM”), which may for example be mounted on a well tree), is regulated by a number of power switching modules (“PSM”), typically housed within a power distribution and protection module (“PD&PM”), which is in turn part of a subsea distribution unit. Each PSM is typically a silicon controlled rectifier-based AC power static switch, as is known in the art.
A drawback with such systems is that well operators are unable to determine whether the PSMs are functioning correctly, or to diagnose a PSM failure.